Pulse time modulated multiplex system



April 26, 1949. I?. DQ GRIEG 2,468,059

PULSE TIME MODULATED MULTIPLEX SYSTEM Filed Oct. 30,' 1945 7Sheets-Sheet l I A Hz BASE wAvE GENERATOR 7`;|NAL a (4 a 3, MOOULATOR oDF'gf' CLIPPER cLIRPER SIGNAL c ,4r 53 5I 5I F a PHASE MOOULATOR D'Fg,6| SI-IIFrER cLIPRER CLIPPER M 5( TRIGGER SIGNAL d E @.RCU'T fsc 54 52se R PHASE MODULA mnqrl FROM OTHER SIGNAL SYSTEMS sI-IIFTER cLIPRERcLIPPER x I TO OTHER SIGNAL SYSTEMS FIG. I

ATTORNEY April 26, 1949. D. DL GRIEG l `ULSE TIME MODULATED MULTIPLEXSYSTEM '7 Sheets-Sheet 2 Filed Oct. 30, 1945 NGE mm Tl Nm m mD D A N O Daux-2 A TTORNEV April 26,y 1949.

Filed OCI.4 30,V 1945.

FROM RECEIVER lOl loo

\ CHANN EL CLIPPER CHANNEL c ld. CLIPPER CHANNEL c 'F CLIPPER 05DIFFEREN IATOR DIFFERENT IATOR 07 DI FFEREN IATOR FIG. 5

D. D. GRIEG PULSE TIME IIIODULIATED MULTIPLEX SYSTEM IGNAL a.

IMODULATOR l cLI PP E R -I ao SIGNAL b Monu ATon cLIPPER IGNALE 78MoDuLAToR CLIPPER E GNALy 94 R SIGNAL 'F 95 MoDuLAToR l cLIPPER 97IGNALI "9 x 1,

To TRANSMITTER MODULATOR CLIPFER MODULATOR C LI PPER PHASE INVERTERCLIPPER CLIPPER IIE 22 PULSE TIME [I IA PHASE INVERTER IIC I2 PULSE TIMEDEMoDULATo SGNA'- III |25 PULSE TIME Cl" PPER DEMoDuLAToR SIGNAL PHASEINVERTER IIe as PULSE TIME CLPPER DEMoDuLAToR ")SIGNAI- 4 IN VEN TOR.DONALD D. GRI EG A T'TORNEI/ April 2 6, 1949.

Filed oct. :5o. .1945

'7' Sheets-Sheet 4 R M I x E R M -H-I U I LI I@ P m u n. a o m A RT w RTHRT R El El El R I GU GU GU E Gc. Gc Gc G m mm mm ma m Tc T.c Tc m w 7.Ib .m MIXER MIXER `IMIXER O M r m I R. s R w m e F o 5 T M T T T.. T 3MR lR AR MR MR MR I, TE TE ne TE TE IE NP NP NP NP NP NP EP EP EP EP EPEP RH. RI RI RI RU RU EC EL EL EL EC EC F FC FC FC F F, u .u F. W W w DD D D D D 5 5. ,l IM l, ...non IRR vIR lR 3 0 O 3 Tm. TW TW TE ,TH TE RMp mp. MP up P up BE uw um Uw.. um um. um UP DL DL DL DL DL DL Om 0c ocOC `0 OC OC DI. M M M M. ..M M C u. c d F L L L L L A A A. A N N M N N Mw m m m m s w s s s s m D w 2 .r 1. l u ER 3 3 w 4 4 E 1 No I A I M MD TYE E E IR wm @L mm a SE EH Ev Rv HV T Am DD DM DN. DM O BG o INVENTOR.DONALD D. GRIEG A TToR/vgy '7 sheets-sheet 5 I DELAY DEVICE |93 --IPULSE TIME al. DEMODULATOR oIe l *t 2o;

DELAY DEVICE PULSE TIME DEMODU LATOR PULSE TIME DEMODULATOR cLIPPERPuLsE TIME l'l'wed-VDEMODULATDR D. D. GRIEG PULSE TIME MODULATEDMULTIPLEX SYSTEM PHASE DIFFER- ENTIAT- OR PULSE r 209 TRAIN l SELECTOR Ia DIFFER- ENTIATDR l L April '26, 1949.

Filed OCI. 5o, 1945 IF RDM RECEIVER `2I\| I-EI'cL IZ DELAY DEVICE |96PULSE TIME DEMODULTOR zIa PULSE TIME DEMODULATOR CLIPPED LEVEL INVENTOR.DONALD D. GRIEG BY ATTORNEY MINDER PHASE DIFFER- ENTIATDR TIME PU LSETRAIN SELECTOR CHAN NEL NUMBERSI RECEIVED WAVE To OTHER MIXER cLIPPERsWIDTH sELEc'TED MULTI-VIBRAToR-..

DELAYED MIxED a cLIPRER.-

DIFFERENTIATED E CLIPPED April 26, 1949. D, D, GRIEG I 2,468,059

PULSE TIME MODULATED IVIULTIPLEX vSYSTEM Filed OGI.. l150, 1945 '7Sheets-Sheet 6 +21 L234 239 f2 40 fail F OM' l I RECEIVER 24 2145 23a III 242 243 l E 233 l f I l y GROUP 1 MIXER CHANNEL c d CLIPPER 265sEPARATOR a La 4 DEMODULA'roRs V--P-i---f---P--- 214 I I' l GROUP 1r ipI DELAY MIXER l CHANNEL .9h I DEVICE CLIPPER sEPARAToR a l 6B :273OEMODULAToRs 235 GROUP m GROUPnI CHANNEL j; l sEPARAToR sEPARA-IOR a En275*DEIAOIzIULA-roRs E 277 TO OTHER GROUP SEPARATORS Y TO TRANSMITTER TOOTHER DELAY DEVICES AND MULTI-PLEXING CIRCUITS FIG. II

INVENTOR. DONALD D, GRI EG BY /57 i April 26, 1949. D. D. GRIEG PULSETIME MODULATED MULTIPLEX SYSTEM 7 Sheets-Sheet '7 Filed Oct. 50, 1945FROM RECEIVER CHAN FROM BLOCKING CIRCUIT FROM HIGH Q' CIRCUIT aPI-IAsER-.

FROM MU LTI-VIBRATOR GROUP I FROM M|XERCL|PPER DELAYED BLOCKING WAVE.

GROUP II'.

FROM MIXER-CLIPPER.

TIME

m m n LY N f. 6 a n m L E m T E V A .m W n m m m w 5 B S U A D N W PN EPN P D E UN M UN U .E S OA L OA O X A RH E RH R I B GC D GC G M FIG. I2

f@ lA T TORN E Y Patented Apr. 26, 1949 PULSE TIME MODULATED MULTIPLEXSYSTEM noualu D; Grieg,

Forest Hills, kN. Y., assigner to Federal Telephone andrRadioCorporation, New York,` N. Y., a corporation of Delaware pplicationctober 30, 194.5., Serial No. 625,649

This inventidfl relates to a; multichannel cm- Inurllc'atn SYStem fO'ft'reinslrittln'g'Y and receiving a signal inodl'ilatedA cdnplexpulseWave. More particularly, it deals"` with the' I'n'ethodV and means formultiplexing trains' of complex pulses'to form a complex' pulsevave inwhich both a' leading edge andv a trailing edge o'f each complex pulseis tlle rrofleltd ao'cdlllg t0 different signals.

lt isV an object of this invention to produce a complex signal modulatedpuls and to multiplex such pulses on a ciiplexpulse WaveV in an lecuvemanner'. Y,

Another'olijet is trv'sl't lld receive Such a multiplexed complexoul'sejwave;

Another object is tournul'tiple'x trains of such complex pulses( vrtic"lly'v by stacking tvvo' or'more trains of tl'leno'n' tpff each' tl'le toproduce single train of step'shapd pulses".

Allotlle" Object is t 50th' vertically" and' holzontally multiplex o'fsuch complex pulses to produce a Single train of step'sha'ped' complexpulses.

Anothf olo'jeo't is'to separate and demodulate such r'nl'lltilvle'xedpulse va'ves'.

Another object" is to time modulate different signals on the edgesofeacl'l coipl'ex'y pulse.

Another' object is topovide the' means for carrying out the objects"mentioned alive.

Still other objects" ldlf'ealtllltesl of this invention WillA appear"fln tln'et' tine in the descrip?- tiOn" WhchvllOWS':

Generally sleakilg]-y this invention" crnpises the steps df (1)'pls()(llicir'gV a. c'ollplex pulse wherein its lelicllrlijg dg-eismodulated according t one signal' and its trailingV edge is modulatedaccording t0 a d'iffet signal," as desoriloed in iiiy co`peidilg`v`appltir'lf, Sei. No. 614,079,1le'd Septnbef'l, 1911-5', and of (2)vertically', lo'ifzv'ntally or veftcally' and l'i'nfi'zillfallfyAr`multiplexing such complex pulses to f'rri a complex pulse Wave. y

The SOllllcs 0f Sig'l'gy which zle rndllated onl tl'e coin'plex pulses"may he vfrom code signals, audio signals, vidosig'nals, Orth-e like.

The means fofproduoiiig the trains of complex pulses modulated accordingtothe energy from said signal sourdes" inclu es a base Wave source, suchas a sine' Wave, savftootl Wave, pulse Wave, or the like, having aconstant frequency and at Claims. (Cl. 179-15) least one sloping edge oneach pulse or undulation of the Wave. This base Wave then may be clippedalong the sloping edge', its undulations at different levels varying inaccordance with the energy in a given signal. The resulting train ofpulses clipped from' the base vvavel thus are time modulated inaccordance with the energy of said signal. Other trains of pulses,out-of-ph'ase with at least one time' modulated edge of any other pulsetrain, may beproduc'ed by clipping the base Wave at other levels and/orby' delaying the base Wave so' that a delayed base Wave is producedwhich is out-of-phase with the original base Wave and clipping theresulting delayed hase Wave at the original or' at other levels inaccordance with the energy Afrom' another signal. Two pulse trainshaving time' modulated edges out-of-phase with each other, may becombined to` form a nev'v and complex pulse train in which the leadingedge of each pulse thereof is time modulated according to one" signaland the trailing edge of each pulse thereof is time modulated accordingto another signal channel.

Tvvo or more trains of these new complex pulses are then multiplexed toform a single con'plex pulse Wave'. The multiplexing of trainsy of'these complex pulses, may .be (l) by vertically stacking one or morepulsesv from diiierent pulse trains to produce a step shaped pulse (eachone of the complex pulses having a dilierent Width to permit suchstacking) or (2) by horizontally interleaving groups of two or morecomplex pulse trains the number lo'eing dependent upon the duration ofthe complex pulse; or (.3) byA both vertically and horizontallymultiplexing trains of suchv :conplex pulses. In order to facilitatemodulation-and separation of horizontal multiplexed pulse trains, asynchronizing' pulsemay be interleaved between the complex' pulses atregularv intervals, such as between each similar group of diiiererltsignal channels.

The resulting complex pulse vave, having complex pulses multiplexedthereon', may be transinitted and received loyl any suitable highfrequency means such as by radio, by Wires or the like. The receivedmultiplexed complex pulse Wave is then separated into pulse trainscorresponding to each signal channel transmitted on the complex pulseWave. The thus separated pulse trairiskare separately time demo'dulated.Horizontally multiplexed pulses may be separated by providing a blockingWave to" select only those complex pulses from a given' train' or`grou'p'of signal channels'. Thefwthus" sep'arratedv complex pulse trainis then further separated into pulse`A trains corresponding to eachsignal channel thereon, either by clipping means (if the complex pulseis also vertically multiplexed) and/or by differentiating means toseparate the leading edges from the trailing edges of each complexpulse. If desired, when the complex pulse wave contains bothhorizontally and vertically multiplexed pulse trains, the verticallymultiplexed, or step shaped pulses, may rst be separated by clippingmeans before being horizontally separated by a suitable blocking wave.

These and other features and objects of the invention will become moreapparent upon consideration of the following detailed description ofseveral embodiments of the invention to be read in connection with theaccompanying drawings in which:

Fig. l is a schematic wiring diagram partially in block of oneembodiment for producing a vertically multiplexed complex wave of thisinvention;

Fig. 2 is a graph of the wave forms useful in describing the operationof the system of Fig. 1;

Fig. 3 is a schematic wiring diagram of another system for producing avertically multiplexed complex wave similar to that produced by thesystem of Fig. 1;

Fig. 4 is a graph of the wave forms useful in describing the operationof the system of Fig. 3;

Fig. 5 is a schematic wiring diagram mostly in block of a system forseparating and demodulating a vertically multiplexed wave producedaccording to the system of Fig. 1 or 3;

Fig. 6 is a graph of the wave forms useful in describing the operationof the system of Fig. 5;

Fig. 7 is a schematic block wiring diagram of a system for producing ahorizontally multiplexed complex pulse wave;

Fig. 8 is a graph of the wave forms useful in describing the operationof the system of Fig. 7;

Fig. 9 is a schematic wiring diagram partially in block of a system forseparating and demodulating the complex pulse wave produced in thesystem of Fig. 7;

Fig. 10 is a graph of the wave forms useful in describing the operationof the system of Fig. 9;

Fig. 11 is a schematic block wiring diagram of a system for producing avertically and horizontally multiplexed complex pulse wave;

Fig. 12 is a graph of the wave forms useful in describing the operationof the system of Fig. 11;

Fig. 13 is a schematic wiring diagram partially in block of a system forseparating and demodulating the complex wave produced in the system ofFig. 11; and

Fig. 14 is a graph of wave forms useful in describing the operation ofthe system of Fig. 13.

IIhe following description is divided into three chapters: Chapter I,illustrated in Figs. 1-6, discloses a vertical multiplexing system;Chapter II, illustrated in Figs. 7-10, discloses a horizontalmultiplexing system; and Chapter III, illustrated in Figs. 11-14,discloses a vertical and horizontal multiplexing system.

CHAPTER I Vertical multiplexing system Referring to Figs. 1 and 2, thereis shown a base Wave generator I for producing a base wave such as thesine wave 2, which is connected through lines 3 to a modulator clipper 4which clips a segment 5 out of a sine wave 2 between limits 6 inaccordance with the energy in the signal a introduced through the line Iinto the modulator clipper 4. The clipped segment producing the pulsetrain 8 is then passed through line 9 to the differentiator clipper I8and thence to the mixer II. The details of the modulator clipper 4 anddifferentiator clipper IEB are shown in connection with the circuit formodulating sig- 'nal b below. Since the base wave 2 is clipped along itssloping edge at different levels corresponding to the energy in signala, the edges of the pulses I2 on pulse train 8 vary toward and away fromeach other in accordance with the signal energy a, i. e., the edges ofthe pulses I2 are time modulated according to the energy in signal a.

Since the pulses multiplexed in the system of this invention arecomplex, i. e., having a different signal modulated on the leading edgefrom that of the trailing edge, only one edge of the pulse I2 is neededin producing the complex pulse. Therefore, the leading edge of pulse I2is separated from the trailing edge thereof, by differentiating thepulse train 8 to produce the differentiated pulse train I3 wherein onlythe leading edges of the pulses I2 appear as positive pulses Ill. Thesepulses Ill are removed from the rest of the train I3 by clipping italong the line I5. To prevent overlapping of the pulses of one signalwith those of another, the clipping level limits 6 of the differentsignals may be varied within, different voltage ranges along the slopingedge of the wave, as shown and described later in Fig. 4 or the phase ofthe base wave may be changed and the clipping may take pulses at thesame levels 6 as shown in Fig. 2.

For producing the edge pulse time modulated in accordance with thesignal b, the base wave from the generator I is passed through line I6to the delay mechanism, such as the phase shifter I'I comprising acondenser 8 or a variable resistor I9, to produce the delayed base wave26 shown in dotted lines in Fig. 2. Although the wave 2t is showndelayed an amount so that the leading edge of a pulse train clippedtherefrom is in synchronism with the trailing edge of the p ulse trainof the original base wave no overlap occurs because only the leadingedges of each clipped pulse train are used. Such a delay, however, isnot necessary lprovided there is no overlap between the time modulatedsignal channels of the different signals a. and b. The delayed base wave2S then passes through line 2| into the modulator clipper 22 which maycomprise a double diode 23 and an audio frequency transformer 2li. Thesignal b is then connected to transformer 24 through line 25 and itsenergy varies the level of the clipping segment 5 between the limits 6.The width of the segment 5 is determined by the adjustment of thevariable resistors 26 and 2l. From the plate 28 of the tube 23 iswithdrawn the clipped pulse train 29 having pulses 28u. with leading andtrailing edges time modulated in accordance with the signal b. Thispulse train 29 then passes through line 30 to a diiferentiator clipper3l, which may comprise a diiferentiator circuit consisting of condenser32 and resistor 33, for producing the differentiated pulse train 34.Diiferentiated pulse train 34 isthen passed on to one of the grids ofthe clipper tube 35 which is biased through the resistor 33 so as topass only the positive pulses 36 of the differentiated pulse trains S4by clipping them olf along the line 3l. These Ipositive pulses 36 arethen withdrawn from the plate of tube 35 through the line 38 into themixer II.

The mixer may comprise two triodes 39,:the grids of which are coupled-inparallel with :the lines from the differentiator clippers l and 3|.These triodes 39 prevent venergy in the pulses of one differentiatorclipper circuit Vfrom feedingA back into the circuit of the otherdiiferentiator clipper. From the plates of the triodes 39 .is withdrawna combined complex pulse train 40 through line 4|. The odd numberedpulses .on this train 40 corresponding to the time modulated .signalchannel d and the even numbered vpulses correspond to time modulatedsignal channel b. In order to combine these two pulsesv into a. singlewider complex pulse, the train .40 `is passed to a trigger circuit 42from which is withdrawn the complex pulse train 43 through line 44. Thetrigger circuit 42 may comprise .a pair of triodes `45 .coupled in sucha manner that an'odd numbered pulse causes one of the tubes to nreaneven numbered pulse fires the other tube'which then remains conductiveuntil the next odd numbered pulse lires the first tube again, and so on.Thus, this circuit produces the complex wave 43, which then is. passedthrough line 441 to the mixer45.

Signals c and d may be similarlymodulated on further delayed base waves41 and 48 respectively, produced from the base wave 2 in phase Shifters49 and 50 connected to generator |v through'line I6. These delayed waves,41 and 48 are modulated and clipped in circuits and 5,2 (similar tocircuit 22) from the energy of signals c and d introduced through linesr53. and 5'4, respectively. From the modulator clippers 5t and 52A are`withdrawn pulse trains 55 and 56 which are separately differentiatedand.v clipped in circuits 51 and'. 58 (similar to. differentiatorfclipper circuit 3|) to produce trains of positive pulses l5.9 and 60,respectively. These pulses 59 and 60 are mixed in a mixer 0| to producethe pulse train 62 which is. passed to a trigger circuit 83 (similar to42) -to produce the complex .pulse train 64 which passes to the mixer45, (similar tothe mixer It). From the mixer 46 isvwithdrawn` avertically multiplexed complex step shaped pulse wave 65 through line 65for transmission by a suitable ultra frequency apparatus. In order tovertically stack the complex pulses produced on wave trains 43 andl 64,it is` necessary thaty the basic width of the pulses in each train bedifferent. However, if the pulses had the same width and weresufficiently out-oif-phase with each other to partially overlap acomplex step pulse could be formed wherein theleading edge of one pulsetrain would be on the leading edge of the first step of the step shapedpulse, and thev trailing edge of that pulse on the same pulse' trainwould be. on the trailingedge of the second step of the step shapedpulse, and correspondingly the leading edge of each pulse of the secondpulse` train would be the leading edge on the second' step of the stepshaped pulse and the trailing edge of that pulseon the same second pulsetrain would be the trailing edge of; the rst step ofj the stepshapedpulse. Complex step shaped pulses of this type may be employed4 inscrambling signal channels for secrecy.

Another system for producing trains of complex. pulses and verticallymodulating them on a, com plexwave similar to wave 8,5.isl disclosed inlFigs.. 3 and 4,.wherein61. is. a pulse generatpr producing; 31 91.115@AWave. 63 -WhCh StIaIlSmtiled; 13112011.5511 lille. 69 t0 leading. edgeandl trailing edsewave. Shapers, 1'0 and 1| respectively., v'lheseShapers` produce waves having sloping, .edgeswhich may be media:-`

differentiated. pulsetrain from pulse lator iclipped to form pulsetrains Ahaving rtimed modulated pulses.

`Leading edge wave shaper 10 produces from the base pulse wave 68inverted wave 12 having pulses or undulations with a leading slopingedge 13 through themeans of a tube 14 and condenser 15. .The shaped basewave 12 is then connected through line 18 to a network of modulatorclippers 11, 18 and 19 (similar to modulator clipper 22 shown in Fig. 1)wherein the wave 12 is modulator clipped Vat the different channellevels shown in Fig. 4 to produce pulse trains having time modulatedleading edges only (since trailing edge 8| is vertical) corresponding tothe energy in signals a,-b and c, respectively. The resulting pulsetrains (not shown) are separately passed to the mixer 89 (similarto'mixer shown in Fig. 1).

The .trailing edge wave shaper 1| comprises a delay device 83, a phaseinverter 84, and a differentiator clipper .85. The delay device 83 maycomprise a network of inductances and condensers to yassimilate thetransmission line. The phase inverter 84 may comprise a triode 80, fromthe plate of which is withdrawn the delayed and inverted pulse wave 81through line 88. This wave 81 is thenpassed to the diilerentiator.clipper 85 (similar to 3| shown in Fig..1 without transformer 24)contains circuit elements of suiiicient magnitude to produce a wave ofthe form 89. Wave 89 is then clipped along the line 90 in the tube 85a,to produce a second shaped base wave of positive undulations havingvertical leading edges 9|, in exact alignment and synchronism with thetrailing'edge 8| of wave 12, and having a sloping trailing edge 92complementary to the edge 13 of wave 12. Since the tube 85a inverts thewave 89, a phase inverter 84a similar to 84 is required to produce thepositive undulations of wave 89. These positive undulations are thenpassed through line 93 to the modulator clippers 94, 95 and 96 andclipped at the different channel levels shown in Fig. 4 to produce pulsetrains (not shown) corresponding, respectively, to signals d, e and fintroduced into these modulator clippers, (also similar to the modulatorclipper 22). The separate pulse trains are then passed into the mixer 80from which is withdrawn, through line 91 for transmission, a verticallymultiplexed complex step shaped pulse wave 98 similar to the wave 65.

In Figs. 5 and 6 is shown a system for separating and demodulating avertically multiplexed complex step shaped pulse wave of the typeproduced in the system of Fig. 1 or 3. Such a complex wave is shownagain in Fig. 6 at 99, which is received over line |00 in Fig. 5 andcoupled to the separate channel clippers |0|`, |02, and |03.

The channel clippers |0|, |02 and |03 may be similar to the doubleclipper circuit 22 shown in Fig. 1 without the transformer 24 therein. Aschematic Wiring diagram of such a double clipper is disclosed later inFig. 13. These channel clippers clip off the different steps of thecomplex pulses on wave 99 as shown between the horizontal lines in Fig.6. Since both the leading edge and the trailing edge of each stepcarries a difierent signal channel, each clipped step comprises acomplex pulse train (such as train |04 for signal channels a and b)wherein each pulse carries two signal channels. r'Ihe complexpulsetrains from the clippers |0|, |02 and |03 are then respectivelypassed to the diiierentiators |05, |08, and |01 to separate the leadingfrom the trailing edges of each pulse on the pulse trains. For example,the train |104 is shown at |08. The diierentiated pulsetrains are thenslipped to remove the positive pulses corresponding to signal channel a,c and e in clippers |09, I and respectively. To separate the edge pulsesof channels b, d and f, respectively, the diiierentiated trains from|05, |06 and |01, are passed through the phase inverters ||2, ||3 andH4' to produce an inverted train (similar. to |5 which corresponds tochannel b) which trains are then clipped in clippers ||6, Ill, ||8. (Theclipped time modulated pulse channels for signals a and b are shown byWaves ||9 and |20 respectively.) The separated pulse train channels arethen each separately demodulated in the pulse time demodulators |2|,|22, |23, |24, |25 and |26 from which are withdrawn reproduced signalsa, b, c, d, e, and f, respectively. The pulse time demodulators mayinclude a harmonic generator |21 which produces a wave having slopingedges and preferably is a harmonie of the original base wave y6|produced in the system of Fig. 1 or 3. The addition of a pulse -channeltrain to the sloping edges of such a harmonic wave, produces amplitudemodulated pulses on the. wave, which may be clipped off in tube |28 andpassed through the low pass filter |29 from which is withdrawn thedesired signal, which in this :case is a. More details of such a timedemodulator are disclosed in my copending application Serial No.459,959, led September 28, 1942, U. S. Patent No. 2,416,306, grantedFeb. 25, 1947.

CHAPTER II Horizontal multiplexing system In Figs. 7 and 8 is shown asystem for horizontally multiplexing a series of complex pulses in whicheach pulse has one signal modulated on its leading edge and anothersignal modulated on its trailing edge. This system comprises a base wavegenerator |30 for producing the wave |3| which passes through line |32into a double clipper |33 (similar to that shown in Fig. 13 describedlater) which cuts the top oil of the undulations of wave |3|, to producea train of synchronizing pulses |34 that are passed through line |35 tothe mixer |36.

The signals to be transmitted are modulated from different delayed basewaves out-of-phase with the wave |3|. These different delayed base Wavesare produced from the series of delay devices |31, |38, |39, |40,|4|,`|4'2 and are shown in dotted lines in Fig. 8 at |43, |44, |45, |46,|41 and |48, respectively. The base waves are then modulator clipped,respectively according to signals a, b, c, d, e and f in modulatorclippers |49, |50, I5 |52, |53, |54, to produce a series of pulse trainssimilar to those for signal channels a, and b shown in Fig. 8 as trains|55 and |56. Since the next complex pulse train is composed of pulsescorresponding only to the leading edges of the pulses on trains |55 and|56 these trains are diierentiated to form trains |55a and |56a and thenclip- Vvped to remove only their positive pulses in the" 'rst two of thediferentiator clippers |51, |58,

|59, |60, |6|, |62, respectively. The resulting positive pulse trainsfrom the clippers |51 and |58 are then mixed in mixer |63 (similar tomixer in Fig. 1) from which is withdrawn the pulse train |64 which isthen passed into trigger circuit |65 (similar to trigger circuit |42 inFig. 11) to produce the complex pulse train |66 which is passed to themixer |36. Likewise the pulse trains of signal channels c and d aremixed in mixer |61, triggered in circuit |68, and passed to mixer |36,and similarly pulse trains of signal channels e and f are mixed in mixer|69, triggered in circuit |10, and passed to mixer |36. From mixer |36through line 1| is Withdrawn the horizontal multiplexed complex pulsewave |12, having synchronizing pulses S interleaved between each similargroup of different complex pulse channels. If desired, further signalchannels, besides the six shown, may be produced and interleaved betweenthe synchronizing pulses S. Such additional circuits Would be connectedto other delay devices through line |14 and to the mixer |36 throughline |15.

Figs. 9 and 10 disclose a system for separating and demodulatingthesignals on a horizontally multiplexed complex pulse Wave of the type of|12. Such a Wave is received through line |16 and connected to the pulsewidth selector 11 and the complex pulse train selectors |18, |19, |80.

The pulse width selector 11 (similar to that disclosed in my copendingjoint application Ser. No. 487,072, led May 15, 1943, U. S. Patent No.2,440,278, granted April 27, 1948) separates the synchronizing pulses Son Wave |12 from the wider time modulated complex pulses carrying thesignal channels. This pulse width selector may comprise an amplifyingtube |8| for amplifying the current of the pulse Wave |12, which is thenpassedinto the time constant circuit |82 tuned to be responsive to thewidth of the synchronizing pulses S. The undulations of the timeconstant circuit |82 are damped through damping tube |83 so that onlythe rst undulations having the greatest amplitudes are clipped inclipper circuit of tube |84' to produce the synchronizing wave |85. Fromthis wave |85 is then produced a blocking wave |88 in the multivibrator|81. The circuit of the multivibrator |81 may comprise two tubes |88 andtwo time constant circuits, comprising: (1) variable resistor |89 andcondenser |90 and (2) variable resistor |9| and condenser |92. Theselatter time constant circuits are adjusted so that the pulses on Wave|85 lires one of the tubes |88 which remains conductive for a timesuicient to completely block any one of the signal modulated pulses onwave |12, and then the other tube |88 is red and remains conductiveuntil the next pulse on wave |85 res the rst tube again. This block Wave|86 is then withdrawn through line |93 and connected to the series ofdelay mechanisms |94, |95 and |96, for delaying the wave 86 so it willbein synchronism with each dilerent train of complex pulses on wave |12.

The resulting delayed blocking Waves withdrawn from the delay devicesare then respectively coupled to pulse trainselectors |18, |19 and |80,each of which may comprise a mixer clipper circuit. The mixer clippercircuit may comprise two triodes |91, the grids of which are connectedrespectively to the delayed blocking wave and to the complex pulse wave.Each one of these tubes are biased suiciently so that the composite wave|98 will be clipped. along the line |99 to remove only the desired trainof signal pulses.

This selected complex pulse train is then withdrawn through line 200 andpassed through the diierentiator 20| to produce the differentiated pulsetrain 202 which differentiated pulse train is both (a) clipped alongline 203 and (b) inverted (to produce wave 204) and clipped along line205, to separate signal channels a and b respectively carried on theleading and trailing edges of each pulse of the selected complex pulsetrain. The resulting separated signal channels are pulse timedemodulatedto reproduce the signals a and b withdrawn through lines 206and 201, respectively. This circuit 208 from pulse train selector |18 isthe same as that disclosed for the separation and demodulation of thecomplex pulses described in Fig. above and will be referred tohereinafter as a channel separator and demodulator circuit.

The other complex pulse separated in the pulse selectors |19, |80 andthe channels thereon are separated and demodulated in the channelseparator and demodulator circuits 209, 2|9v (similar to circuit 205)from which are withdrawn Signals c, d, e, and f through lines 2| I, 2I2, 2I3, 2 I4, respectively. Other pulse trains may be selected in asimilar manner and connected to lines 2 I 5, and 2|6 carrying thereceived complex pulse wave and theblocking wave, respectively.

trains are similarly CHAPTER III Vertical and horizontal multiplexingThe vertically multiplexed step Ishaped complex pulses produced by thesystems disclosed in Chapter I may also be horizontally multiplexedaccording to the system In Figs. 11 and 12 there is shown such a systemcomprising a base wave generator 2|1 for generating the Wave 2|8 whichis connected through line 2|9 to the group'I vertical multiplexingcircuits 223 for producing a vertically multiplexed pulse wave 22|containing signal channels a, b, c, d, etc., which is withdrawn throughthe line 222 and to a mixer 223 (similar to I I in Fig. 1). The verticalmultiplexing circuits may be similar to those disclosed in Fig. 1 orFig. 3 above. The wave 2|8 is also passed through line 224 to a suitabledelay device 225 from which is withdrawn the delayed base wave 226,which is then connected to group II vertical multiplexing circuits 221from which is withdrawn a vertically multiplexed pulse wave 228 which ispassed through line 229 of the mixer 223. Still other delay devices andvertical multiplexing circuits may be connected to line 230 to produceother then connected to the mixer 223. From mixer 223 is withdrawn theresulting vertically and horizontally multiplexed complex pulse wave23|, through line 232 for transmission.

In Figs. 13 and 14 is shown a system for separating the channels on a`complex pulse wave oi' the type `shown at 23|. Such a wave is passedthrough line 232 and connected both to a blocking wave circuit 233 andto groups I, II and III, etc., separator circuits 234, 235, 236, etc.This system does not disclose the use of a synchronizing pulse forseparating similar groups of complex pulses as described in the systemof Chapter II, but instead discloses a circuit whereby a blocking wavemay be produced directly from the complex pulses on the wave 23 I.

The blocking Wave circuit 233 'consists of a high-Qcircuit 231, avariable sine wave phaser 238, a double clipper 239, a differentiator240, and a multivibrator circuit 24|. The high-Q- circuit 231 maycomprise a tube 242 and a time constant circuit 243 for smoothing outthe sharp corners on the wave 23| and produce a sine wave which isWithdrawn-through line 244 into the variable sine wave phaser 238consisting of a condenser 245 and a variable resistor 246. The variablesine wave phaser is so adjusted that the leading edge of each positiveundulation on the Waves 241 and 250are in synchronism with 4the grouppulse waves which arek disclosed in Chapter II.

center of the spaces 255 between the complex pulses on the Wave 23|.From the'sine'vvave phaser 238 is withdrawn the delayed sine wave 241through line 248 into the double clipper circuit 239, similar to clippermodulator circuit 22 shown in Fig. 1 but without the transformer 24. Incircuit- 239, the double diode 249 also may act as an amplifier as Wellas a clipper for clipping off the round ends of the wave 241 and therebyproduce the rectangular shaped Wave 250 which is withdrawn from theplate25| of tube 249 through line 252. The resistors 253 and 254 may beadjusted and biased to aid in shaping the square wave 256. rIhe wave 250is then passed to the difierentiator circuit 240 from which is withdrawnthe pulse wave 256. This pulse wave is then passed into themultivibrator circuit 24| to produce the blocking wave 251. Thismultivibrator circuit is similar to the multivibrator circuit |81 shownin Fig. 9, the resistors 253 and 259 in the time constant circuitsthereof being so adjusted as to provide pulses 266 on wave 251 ofsufiicient duration to reach from one space 255 to the next adjacentspace 255 of the same frequency as a given group complex verticallymultiplexed pulse train interleaved on the wave 23|. The blocking wave251 is then passed through line 26| into a group I separator circuit 234which in this case comprises a mixer clipper similar to that disclosedat |18 in Fig. 9. In the mixer clipper the wave 262 is produced andclipped along the line 263 to separate the cornplex verticallymultiplexed pulses 264 of group I. These pulses 264 are then passedthrough line 265 to the group I channel separator and demodulatorcircuits 266 similar to those previously described and from which arewithdrawn the reproducedr signals a, b, c, d, etc.

The group II separator circuits 235 comprises, in addition-to a mixerclipper 261, a delay device 268 for delaying the blocking wave 261 toproduce the delayed blocking wave 269. This delayed wave 269 is mixed inthe mixer clipper v251 to produce the Wave 210 which is clipped alongthe line` 21|. The resulting clipped pulses 212 are then passed throughline 213 to the group II channel separator and demodulator circuits 214which may be similar to those of 256 and from which are withdrawn thereproduced signals e, f, c, h. etc.

Group III separator 236 is similar to the group II separator 235 and thegroup III channel separator and demodulator circuits 215 are similar tothose of group I at 266 lor group II at 214. Still further, groupseparator and demodulator circuits may be connected to the lines 216 and211, if desired.

The foregoing systems may be extended to multiplex channels other thanthose specifically shown, provided a sulcient free .space is maintainedVbetween each of the signal channels to avoid cross talk from one signalchannel to the other. This applies both to the vertical multiplexing andto horizontal multiplexing of vthe time modulated edges of the complexpulsesA produced by the systems of this invention and my copendingapplication, Serial No. 614,019, led September` 1, 1945.

While the principles of the invention have been described inconnectionwith several specific systems it is to be clearly understood that thesedescriptions are made only by way of example and not asa limitation onthe scope of the invention as defined in the objects and the-accompanying claims.

I claim:

1. In a multichannel system means to produce a pulse having verticallydisposed portions yof different Widths and means to time modulate theleading edge with one signal and the trailing edge with another signalof each such portions.

2. A system for multiplexing signal modulated pulses to produce acomplex pulse wave wherein each pulse carries one time modulated signalon a leading edge thereof and another time modulated signal on thetrailing edge thereof comprising: at least two sources of signal energy,means to produce a plurality of pulse trains respectively time modulatedwith energy from said signal sources, said pulses being out-of-phase`with each other, means to combine two pulses from diierent pulse trainsto form a single new pulse train, and means to multiplex a plurality ofsaid new pulse trains to produce said complex pulse wave.

3. The system of claim 2 wherein the means for multiplexing includesmeans to superimpose the pulses of said new pulse trains to produce astep shaped pulse on said complex pulse wave.

4. The system of claim 2 wherein the means for multiplexing includesmeans to interleave the pulses of said new pulse trains on said complexpulse wave.

5. The system of claim 2 wherein the means for multiplexing includesmeans to superimpose the pulses of said new pulse trains to produce stepshaped pulses and means to interleave said step shaped pulses on saidcomplex pulse wave.

6. The system of claim 2 wherein said means for producing a plurality ofpulse trains includes means to produce a base wave having a slopingedge, and means to clip said base wave along said sloping edge atvarious levels corresponding to the energy from said signal sources.

7. 'Ihe system of claim 2 wherein the means for producing a plurality ofpulse trains includes a base wave source, and means to produce twosimilar waves, out-of-phase with each other, from said base wave.

8. A system for multiplexing signal modulated pulses to produce acomplex pulse wave wherein each pulse carries one time modulated signalon a leading edge thereof and another time modulated signal on thetrailing edge thereof comprising: at least two sources of signal energy,a base wave source, means to change the phase of said base wave, meansto produce pulse trains from the original base wave and the base wavesout-of-phase with the original base wave, means for respectivelymodulating the pulses of said trains with energy from said signalsources, means to interleave the pulses of said pulse trains to producea new pulse wave means to combine successive pairs of pulses on said newpulse wave to form a series of single pulses each bearing two modulatedsignal channels, and means to multiplex a plurality of the resulting newpulse waves to produce said complex pulse wave.

9. The system of claim 8 wherein said means to combine successive seriesof pulses comprises a trigger circuit means.

10. The system of claim 8 wherein said means to produce one of saidpulse trains includes a diierentiating means and a clipping means.

11. A system for multiplexing'signal modulated pulses to produce acomplex pulse wave wherein each pulse carries one time modulated signalon a leading edge thereof and another time modulated signal on thetrailing edge thereof comprising: at least two sources of signal energy,

means to produce a plurality of pulse trains respectively time modulatedat one edge per pulse with energy from said signal sources, meanscontrolling said pulse trains so that the unmodulated edges ofcorresponding pulses of said pulse trains coincide, means to combinecorresponding pulses from each train into a single pulse on a new pulsetrain, and means to multiplex a plurality of said new pulse trains toproduce said complex pulse wave.

12. The system of claim 11 wherein said means to produce a plurality ofpulse trains includes a base wave source, means for separating said basewave to produce two base pulse waves one of which has pulses with asloping leading edge and the other of which has pulses with a slopingtrailing edge, said base pulse waves being outof-phase with each other.

13. A communication system for transmitting and receiving a complexpulse wave having more than two signal channels modulated thereoncomprising: more than two sources of signal energy, means to produce aplurality of pulse trains respectively time modulated with energy fromsaid signal sources, said pulses being out-ofphase with each other,means to interleave the pulses of said pulse trains to produce a, newpulse wave, means to combine successive pairs of pulses in said newpulse waves to form a series of single pulses each bearing two signals,means to multiplex a plurality of the resulting combining pulse waves toproduce a complex pulse wave wherein each pulse carries at least onetime modulated signal in a leading edge thereof and another timemodulated signal on the trailing edge thereof, means to transmit saidcomplex pulse wave, means to receive the complex pulse wave, means toseparate said complex pulse wave into pulse trains corresponding to eachof said signals modulated thereon, and means for demodulating each ofsaid pulse trains.

14. The system of claim 13 wherein said means for multiplexing includesmeans to superimpose the pulses of said new pulse trains to produce astep shaped pulse on said complex pulse wave.

15. The system of claim 13 wherein the means for multiplexing includesmeans to interleave the pulses of said new pulse train on said complexpulse wave.

16. The system of claim 13, wherein said means for multiplexing includesmeans to superimpose the pulses of said new pulse trains to produce stepshaped pulses and means to interleave said step shaped pulses on saidcomplex pulse wave.

17. A communicating system for transmitting and receiving a complexpulse wave having horizontally multiplexed pulses thereon wherein eachof said pulses carries one time modulated signal on a leading edgethereof and another time modulated signal on the trailing edge thereof,comprising: more than two sources of signal energy, a base wave source,means controlled by said base wave to produce a synchronizing pulse,means controlled by said base wave to produce a plurality of pulsetrains respectively time modulated with energy from said signals, allthe edges of said pulses produced from said base wave being out-of-phasewith each other, means to combine two pulses from `dilerent pulse trainsto form a single new pulse train, means to horizontally multiplex aplurality of said new pulse trains to produce a complex pulse wavehaving a synchronizing pulse interleaved at regular intervals betweenthe complex pulses thereon,

means to transmit said complex pulse wave, means to receive said complexpulse wave, means to separate the signals modulated on said complexpulse Wave comprising a blocking wave controlled by the synchronizingpulse on said complex pulse wave, means for separating the signalchannels on the separated pulses to produce pulse trains correspondingto each signal carried by said complex pulse wave, and separate means todemodulate each of said separated pulse trains.

18. A method of communicating a complex pulse Wave carrying a pluralityof multiplexed time modulated signals, wherein each pulse on said wavecarries one time modulated signal on a leading edge thereof and anothertime modulated signal on the trailing edge thereof comprising: producinga plurality of pulse trains respectively time modulated with energy fromsaid signals, said pulses being out-of-phase with each other, combiningtwo pulses from different pulse trains to form a single new pulse train,multiplexing a plurality of said new pulse trains to produce saidcomplex pulse wave, transmitting said complex pulse wave, receiving saidcomplex pulse wave separating the signals on said received complex pulsewave into separate pulse trains corresponding to each of said signals,and separately demodulating said separated pulse trains to reproducesaid signals.

19. In a communication system for receiving a complex pulse wave havingmultiplexed complex pulses thereon, said complex pulses having one timemodulated signal on a leading edge thereof and another time modulatedsignal on the trailing edge thereof, said complex pulses beinghorizontally multiplexed in an interleaved manner, means for separatingthe wave into pulse trains corresponding to each signal modulated onsaid complex wave, said separating means including means for producing ablocking Wave having the same frequency as a given train of complexpulses to separate a given pair of signal channels, and means forseparating said separated pairs of signals comprising diierentiatingmeans, and means for demodulating each of said separated pairs ofsignals.

20. In a communication system for receiving a complex pulse Wave havingmultiplexed complex pulses thereon, said complex pulses having one timemodulated signal on a leading edge thereof and another time modulatedsignal on the trailing edge thereof, said complex pulses being bothvertically and horizontally multiplexed on said complex pulse wave,means for separating the wave into pulse trains corresponding to eachsignal modulated on said complex Wave, said separating means including ablocking wave for separating the horizontally multiplexed complexpulses, a clipping means for separating the vertically multiplexedpulses, and a diierentiating means for separating the leading edge fromthe trailing edge of the pulses of the resulting separated pulse trainto thereby separate the signal channels, and means for demodulating eachof said separated edges to reproduce the signal.

DONALD D. GRIEG.

REFERENCES CITED The following references are of record in the file oithis patent:

UNITED STATES PATENTS Number Name Date 2,266,194 Guanella Dec. 16, 19412,406,790 Beatty et al Sept. 3, 1945 2.419.292 Shepard Apr. 22, 1947

